Loading coil structure



July -1, 1958 Y R. E. BASSETT, JR 2,841,789

LOADING COIL STRUCTURE Filed March 18, 1955 4 INVENTOR I4 I? E. Basseib, Jr. W,%WV%

ATTORNEYS United States Patent LOADING con. STRUCTURE Rex E. Bassett,.Ir., Fort Lauderdale, Fla., assignor to Bassett Research Corporation,Detroit, Mich., a corporation of Michigan Application March 18, 1955,Serial No. 495,268 3 Claims. (0. 343-149 This invention relates to anincluding a novel inductor for resonating the antenna system to desiredfrequency.

The novel loading coil which is the primary subject of this inventionmay not only be applied toantenna systems but may also be used to provethe stability and operation of, any radio frequency generator,transmitter or receiver.

- 'In the present instance the novel coilstructure is in-' In. the pastsuch loading coils have been. wound on a suitable form, using thedesired :wire, and left 'unpro tected to the elements. They thenproduced one resonant frequency and one degree of .eificiency at onlyone specific condition of humidity. Thus, during arainstorm orother'inclement weather conditions these prior structures became highlyinefiicient or lost their efficiency altogether.

' The present invention contemplates the provision of an inductor whichis completely encased :and protected in a sealed plastic cylinder whichis evacuated and then filled with an inert gas, such as helium,"theobject being to eliminate the deleterious efiects on the coil ofchanging humidity, dirt, dust, salt spray, corrosion and oxidation. The.primary advantage of the nw protected coil structure lies in the factthat distributedcapacity across the. coil remains constant, regardlessof: weather conditions, resonance is stabilized and constant efiiciencyfor' the tuned circuit results.

These same advantages follow whether the coil is used in an antennasystem or in the transmitter or receiver circuits.

It is therefore a primary object of this invention to evolve an improvedinductor coil for radio frequency circuits in which the coil iscompletely enclosed and protected in an evacuated casing so as to beimpervious to the deleterious effects of the elements.

It is a further object of this invention to provide such an improvedloading coil which is particularly adapted to antenna systems and whichwill maintain such systems at the desired frequency, regardless ofweather conditions.

A further object of this invention is to provide such a loading coil ofimproved structure and efficiency.

Other and further objects of this invention will become apparent as thisspecification proceeds.

Referring to the drawings, Fig. l is a crosssectional View, taken on thevertical axis, of an improved loading coil made in accordance with thepresent invention;

improved antenna system the lower antenna rod and the Fig. 2 is a planview from above, partially brokenaway, of the improved coil structure;

Fig. 3 is a perspective view of an antenna system incorporating theimproved loading coil.

In the drawings, 5 indicates the improved loading coil structure whichcomprises an outer casing or plastic tube 6 of heavy construction whichis closed at its extremities by plastic end discs 7 and 8 which areappropriately cemented or sealed thereto with ethylene dichloride or anepoxy resin, as shown in Fig. 1 of the drawing. Plastic end discs 7 and8 are preferably bored at their centers to receive metal end fittings 9and 10 which are appropriately cemented or otherwise aflixed Within thecenters of end plates 7 and 8, respectively. Metal end fittings 9 and 10are preferably centrally recessed and screw threaded, respectively, at11 and 12 to receive the screw threaded extremities of the upper whiprod 13 of the antenna and the screw threaded upper extremity of thelower antenna rod 14. Center support rod'16, which is preferably a heavyplastic rod, is shown suitably bored at its upper and lower extremitiesto receive and support the knurled inner extremities of metal endfittings 9 and 10, between which it is rigidly affixed and for which itprovides insulation and central support.

Extending rectangularly from the inner extremities of metal end fittings9 and 10, through red 16, are metal pins 17 and 18 which serve asterminal contacts for the extremities 19 and 20 of the coil structuresupported within the casing 6.

Coil 22 is shown supported within plastic casing 6 by means of a seriesof vertically disposed plastic spacer members 23 which maintain coil 22in its proper vertical position within casing 6 and which are preferablyapplied over coil 22 against the inner peripheral wall of casing 6 bymeans of suitable plastic cement or other bonding material. A series offive of these spacers 23 are preferably provided to maintain coil 22 inits proper vertical position within casing 6. As will be seen from Fig.l, the upper, free extremity 19 of coil 22 is affixed to contact pin 17of metal end fitting 9 and its lower, free extremity 20 is affixed tocontact pin 18 of lower end fitting 10.

In order more completely to protect coil 22 from umidity and otherdeteriorating effects casing 6 is preferably evacuated, after the coiland casing structure has ,been completely assembled, through a smallvent 24 tapped in the lower end which a small screw 25 is insertedthrough vent 24 to seal the casing 6 and a layer of plastic or othersealing material 26 is applied over the head of screw 25 to complete thesealing of the casing.

Prior to its insertion into the casing 6 coil 22 is wound to produce thedesired resonant frequency for the installation and by virtue of thesubsequent evacuation and sealing of the casing 6 coil 22 will remainpermanently at this desired resonance to insure the maintenance of thedesired resonant frequency, regardless of humidity or other outsideconditions.

When this improved sealed coil structure is utilized, as shown, in anantenna system it produces a constant resonant frequency which isunaffected by outside weather conditions or humidity.

In Fig. 3 one embodiment of an improved antenna system including thenovel coil structure is illustrated. This antenna comprises broadly analloy base rod 27 of substantially one and a half inch diameter which isswivelly mounted at its base for installation on a deck, wall or othersurface by a base insulator and swivel mount 28 into which the lowerextremity of base rod 27 is fitted. The antenna structure is supportedin vertical position by quick disconnect insulator member 29 comprisinga recessed insulator base 30 and a pivotal catch member 31 which may beopened to allow the antenna to be swung to horizontal position. At, its.upper extremity base rod 27 is shouldered at 32 and is reduced intoscrew threaded extension 14 which screws into screw threaded lowerrecess 12 of lower. metal end fitting 10 of the evacuated coil structure5. Antenna whip rod 13, which is preferably formed of noncorrosiveFiberglas, is shown disposed above coil 5 and supported thereupon by itslower shouldered extremity 33, its lower extremity being screw threadedabout its outer periphery to screw into screw threaded recess 11 inupper metal end fitting 9 of the evacuated coil assembly 5. Thepreferable over-all length of the' antenna system is twenty feet; Thislength may be varied as desired, depending upon the nature and wattageof the radio telephone with which the antenna is being utilized 7 As theinductor coil 22 is connected atits lower extremity 20 to pin 18 ofmetal end fitting and at its upper extremity 19 to pin 17 of upper metalend fitting 9 and as the upper and lower antenna rodsscreW-threadedlyengage metal end fittings 9 and 10 respectively, the inductor coilbecomes an integral part of the antenna system and maintains the antennasystem at the desired resonant frequency at all times.

With the antenna system shown here, incorporating the improved high Qinductor, any radio telephone installation will give an extremely highperformance. For example, with this antenna system a twenty-five wattset will out-perform a fifty watt set with a conventional antenna.

As has been hereinbefore stated, the improved inductor herein describedwill greatly improve the stability and operation of any radio frequencygenerator, transmitter or receiver and its adaptability to such systemswill be readily apparent to anyone skilled in the art.

The use of the improved coil structure guarantees the production of oneresonant frequency, frequency is stabilized and constant efficiency forthe tuned circuit results. These advantages result whether the coil isused in antenna, transmitter or receiver circuity,

By virtue of the provision of the heavy centersupport rod 16 into theextremities of which metal end fittings 9 and 10 are set, and whichsupports end plates 7 and v8 and casing 6 of the coil structure, theentire coil structure is of extreme strength and able of withstandingheavy shocks. strength further insures the efficient operation of thestability and is cap- This high physical coil structure under any and"all conditions of use and weather.

The invention is susceptible of numerous alternative embodiments withoutdeparting from the spirit thereof. Changes may be made in the structuraldesign of the casing and elements thereof within wide limits withoutdeparting from the-spirit of the invention.

Attention is directed to the appended claims for a limitation ofthe-scope ofthis invention.

What is claimed 'is:

1. In a resonant evacuated coil structure, a cylindrical casing, end,plates. affixed to. the extremities ,of said casing, metal end fittings,afiixed through the centers of said end plates, a heavy dielectric rodextended on the axis of said casing receiving the inner extremities ofsaid metal end fittings, a wire coil disposed about the interior ofsaidcasing andzincontact'with said metal end fittings at; its: upperandlower extremities, whereby said coil structure may be incorporated inan electrical system by contactinggsaid: meta-l= end fittings in saidsystem.

2..In.a'.loading coil for: resonating an antenna to desiredfrequency,acylindrical plastic casing, plastic end plates afiixed over: theextremities'of said casing, metal end fittings disposed through thecenters of said end plates, a heavy dielectric: rodextendinglongitudinally of said casing v receiving and: supporting theinner extremities-of said metal; end fittings, a loading coil resonatedto a desired frequency disposed about-the inner periphery of said casingand contacting said: metal end fittings atits. extremities-,7 wherebysaid coil structure may be incorporated; in--anelectrical: system bycontacting. said metal end fittings in said systemr 3. In a:loadingzcoil'for resonating a radio frequency system todesiredfrequency, a cylindrical casing, plastic end-.platesrfitted tothe: extremitiesof said casing, metal end fittings supported.inthecentersof said end plates, a dielectricrodwithin said casingsupporting and insulating, said metalendt-fittings, a loadingcoil'supported againstztheinner peripheryv of said'casing and in contact withsaid end-fittings respectively atits upper and lower extremities, aninertJgas filling said casing, wherebysaid loading coil may be utilizedfor resonating a radio fie quencysystem to desired frequency. bycontacting said metal end fittings in. said system.

References itlgitedfinihe. file. of this patent ;UNIT-ED STATES PATENTS1,933,959 Block Nov. 7, 1933 2,206,820 I v Mydlilj 'Iuly 2, 19402,552,999 Pannell'et al May 15, 1951' 2,714,184 I Peck -r-.,-t July26,1955-

